تحت رژيم هاي مختلف آبياري PYRUS SEROTINA REHD مطالعه تجمع پرولين و روابط آبي برگ در 9 ژيوتيپ گلابي آسيايي

Study of proline accumulation and leaf water relations in nine Asian Pear (Pyrus serotina Rehd.) genotypes under different irrigation regimes

Improving fruit tree germplasm is an important task in Iran to use them in fruit tree breeding program, because Iran is one of the arid and semi-arid regions in the world. So, cultivar introduction and study of stress resistance source in fruit tree is essential in fruit tree breeding program. This research was fulfilled on nine Asian pear genotypes (Pyrus serotina Rehd.) that introduced to our country from International Horticultural Congress from Belgium in 1998. Asian pear genotypes named KS6, KS7, KS8, KS9, KS10, KS11, KS12, KS13 and KS14. Also a native Pear cv. Shah Miveh was used. Three irrigation treatments were applied: control, mild stress and severe stress. The control was irrigated to provide non-stress conditions. In mild drought stress, plants irrigated when soil water potential reached - 0.5 MPa and severe drought stress, plants irrigated when soil water potential reached -I MPa. Some drought resistance trails such as plant water status, proline accumulation, relative water content (RWC), predawn leaf water potential (PLWP) and their correlation were studied. Results showed that proline accumulation increased in drought stress treatments ranged between 2-7 times more than control. RWC decreased in drought stress treatments and was severed in cv. Shah Miveh (65.15%). There was a negative correlation between proline accumulation and RWC in all genotypes (r-0.99-.83). PLWP, also decreased under drought stress treatments(i= 0.99-0.9). Proline accumulation in plant acts as osmotica or cytoplasmic enzyme and cell structure protectant. As the results shown, Asian pear genotypes differ in RWC and cvs. KS8, KS9 and KS1 1 showed greater RWC than Shah Miveh under stress treatments.